The invention is generally related to the field of forming semiconductor devices and more specifically to forming the protective overcoat on semiconductor devices.
In fabricating an integrated circuit, bondpads are formed in the final metal interconnect layer. This can be accomplished with at least two different methods. In the first method the final metal interconnect layer is deposited. After which, a protective overcoat is formed. Bondpad windows are then patterned and etched into the protective overcoat. In the second method, the protective overcoat is first formed. The bondpad windows are patterned and etched into the protective overcoat. The final metal layer interconnect is then deposited to fill the bondpad windows. A final pattern and etch is accomplished to remove the remaining excess metal. Traditionally, silicon-nitride is used in the protective overcoat with an underlying oxide layer. Silicon-nitride is deposited using SiH4 and NH3. Common to these methods of depositing and forming the final metal layer interconnect and protective overcoat is a sinter performed at 435xc2x0 C. in H2/N2 for 30 minutes. This sinter is always performed after the completion of the steps described above.
There are many types of integrated circuits. There are logic ICs, DRAMs (dynamic random access memories), SRAMs (static random access memories), analog ICs, digital signal processors, mixed signal processors, etc. There are also special integrated circuits referred to as FLASH devices or FLASH memories. FLASH devices are UV (ultra-violet light) programmable. FLASH devices require a protective overcoat that is UV transmissive. For this reason, silicon-oxynitride may be used as a protective overcoat for FLASH devices.